Backscattering properties of optical and electromagnetic waves with remote sensing of cirrus clouds by 0.355 mm polarizing lidar and 94 GHz radar
V.A. Shishko1,2, D.N. Timofeev1, A.V. Konoshonkin1, N.V. Kustova1, N. Kan1, I.V. Tkachev1, K. Masuda3, H. Ishimoto3, H. Okamoto4, A.G. Borovoi1
1V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, Tomsk, Russia
2National Research Tomsk State University, Tomsk, Russia
3Meteorological Research Institute, Nagamine, Japan
4Kyushu University, Kasuga, Japan
Keywords: light scattering, lidar, radar, physical optics, discrete dipole approximation, atmospheric ice crystal, cirrus cloud
Abstract
The problem of electromagnetic scattering on ice crystals of cirrus clouds was solved for 94 GHz radar (wavelength 3189 mm) and lidar (wavelength 0.355 mm) with the refractive indices of ice - 1.7864 + 0.0032 × i and 1.3249 + 0 × i respectively. The scattering matrices were calculated within the physical optics approximation and the discrete dipole approximation for the case of randomly oriented particles. The particle sizes varied from 4 to 1000 mm. It was possible to correctly calculate the ratio of the radar and lidar signals in the backscattering direction, called the radar-lidar ratio. The ratio was obtained for the wide particle size distribution for typical shapes of cirrus cloud ice crystals. It is shown that this ratio can be used to estimate the size of ice crystals in cirrus clouds.
|
